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![[Figure 5]](ky3231fig5mag.jpg)
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Figure 5
In a DASH crystal structure solution of chlorothiazide, the C2—C1—S1−N1 torsion angle may adopt values of x° (a), x + 120° (b) or x − 120° (c), due to the negligible difference in X-ray scattering between =O (8 e−) and –NH2 (9 e−). Consequently, the presence of all three –S(=O)2–NH2 orientations in the ensemble of DASH output solutions is to be expected. This type of ambiguity also arises with the rotation of a carboxyl group (O=C—OH, typically two orientations at x° and x + 180°) and the orientation of a mesylate anion [CH3—S(=O)2—O−, up to four orientations]. While Rietveld refinement against a high-quality high-resolution VCT dataset may be able to resolve these cases, hydrogen-bond geometry analysis and periodic DFT-D calculations offer superior discrimination. |
![[Figure 5]](ky3231fig5.jpg)
 | STRUCTURAL CHEMISTRY |
ISSN: 2053-2296
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